/*
* A Base64 Encoder/Decoder.
*
* This class is used to encode and decode data in Base64 format as described in RFC 1521.
*
* This is "Open Source" software and released under the http://www.gnu.org/licenses/lgpl.html GNU/LGPL license.
* It is provided "as is" without warranty of any kind.
* Copyright 2003: Christian d'Heureuse, Inventec Informatik AG, Switzerland.
* Home page: http://www.source-code.biz
*
* 
* Version history:
* 2003-07-22 Christian d'Heureuse (chdh): Module created.
* 2005-08-11 chdh: Lincense changed from GPL to LGPL.
* 2006-11-21 chdh:
*  &nbsp; Method encode(String) renamed to encodeString(String).
*  &nbsp; Method decode(String) renamed to decodeString(String).
*  &nbsp; New method encode(byte[],int) added.
*  &nbsp; New method decode(String) added.
*/
/*
 * Modified by Jacob Davies, 2010.
 */

package org.itemscript.core.util;

/**
 * Base64 encoding/decoding utility class.
 * 
 * @author Christian d'Heureuse
 */
public final class Base64 {
    // Mapping table from 6-bit nibbles to Base64 characters.
    private static char[] map1 = new char[64];
    private static char[] urlMap1 = new char[64];
    // Mapping table from Base64 characters to 6-bit nibbles.
    private static byte[] map2 = new byte[128];
    static {
        int i = 0;
        for (char c = 'A'; c <= 'Z'; c++)
            map1[i++] = c;
        for (char c = 'a'; c <= 'z'; c++)
            map1[i++] = c;
        for (char c = '0'; c <= '9'; c++)
            map1[i++] = c;
        map1[i++] = '+';
        map1[i++] = '/';
    }
    static {
        int i = 0;
        for (char c = 'A'; c <= 'Z'; c++)
            urlMap1[i++] = c;
        for (char c = 'a'; c <= 'z'; c++)
            urlMap1[i++] = c;
        for (char c = '0'; c <= '9'; c++)
            urlMap1[i++] = c;
        urlMap1[i++] = '-';
        urlMap1[i++] = '_';
    }
    static {
        for (int i = 0; i < map2.length; i++)
            map2[i] = -1;
        for (int i = 0; i < 64; i++)
            map2[map1[i]] = (byte) i;
    }

    /**
    * Decodes a byte array from Base64 format.
    * No blanks or line breaks are allowed within the Base64 encoded data.
    * @param in  a character array containing the Base64 encoded data.
    * @return    An array containing the decoded data bytes.
    * @throws    IllegalArgumentException if the input is not valid Base64 encoded data.
    */
    public static byte[] decode(char[] in) {
        int iLen = in.length;
        if (iLen % 4 != 0)
            throw new IllegalArgumentException("Length of Base64 encoded input string is not a multiple of 4.");
        while (iLen > 0 && in[iLen - 1] == '=')
            iLen--;
        int oLen = (iLen * 3) / 4;
        byte[] out = new byte[oLen];
        int ip = 0;
        int op = 0;
        while (ip < iLen) {
            int i0 = in[ip++];
            int i1 = in[ip++];
            int i2 = ip < iLen ? in[ip++] : 'A';
            int i3 = ip < iLen ? in[ip++] : 'A';
            if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
                throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
            int b0 = map2[i0];
            int b1 = map2[i1];
            int b2 = map2[i2];
            int b3 = map2[i3];
            if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
                throw new IllegalArgumentException("Illegal character in Base64 encoded data.");
            int o0 = (b0 << 2) | (b1 >>> 4);
            int o1 = ((b1 & 0xf) << 4) | (b2 >>> 2);
            int o2 = ((b2 & 3) << 6) | b3;
            out[op++] = (byte) o0;
            if (op < oLen) out[op++] = (byte) o1;
            if (op < oLen) out[op++] = (byte) o2;
        }
        return out;
    }

    /**
    * Decodes a byte array from Base64 format.
    * @param s  a Base64 String to be decoded.
    * @return   An array containing the decoded data bytes.
    * @throws   IllegalArgumentException if the input is not valid Base64 encoded data.
    */
    public static byte[] decode(String s) {
        return decode(s.toCharArray());
    }

    /**
    * Encodes a byte array into Base64 format.
    * No blanks or line breaks are inserted.
    * @param in  an array containing the data bytes to be encoded.
    * @return    A character array with the Base64 encoded data.
    */
    public static char[] encode(byte[] in) {
        return encode(in, in.length);
    }

    /**
    * Encodes a byte array into Base64 format.
    * No blanks or line breaks are inserted.
    * @param in   an array containing the data bytes to be encoded.
    * @param iLen number of bytes to process in <code>in</code>.
    * @return     A character array with the Base64 encoded data.
    */
    public static char[] encode(byte[] in, int iLen) {
        int oDataLen = (iLen * 4 + 2) / 3; // output length without padding
        int oLen = ((iLen + 2) / 3) * 4; // output length including padding
        char[] out = new char[oLen];
        int ip = 0;
        int op = 0;
        while (ip < iLen) {
            int i0 = in[ip++] & 0xff;
            int i1 = ip < iLen ? in[ip++] & 0xff : 0;
            int i2 = ip < iLen ? in[ip++] & 0xff : 0;
            int o0 = i0 >>> 2;
            int o1 = ((i0 & 3) << 4) | (i1 >>> 4);
            int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
            int o3 = i2 & 0x3F;
            out[op++] = map1[o0];
            out[op++] = map1[o1];
            out[op] = op < oDataLen ? map1[o2] : '=';
            op++;
            out[op] = op < oDataLen ? map1[o3] : '=';
            op++;
        }
        return out;
    }

    public static char[] encodeForUrl(byte[] in) {
        int iLen = in.length;
        int oDataLen = (iLen * 4 + 2) / 3; // output length without padding
        int oLen = ((iLen + 2) / 3) * 4; // output length including padding
        char[] out = new char[oDataLen];
        int ip = 0;
        int op = 0;
        while (ip < iLen) {
            int i0 = in[ip++] & 0xff;
            int i1 = ip < iLen ? in[ip++] & 0xff : 0;
            int i2 = ip < iLen ? in[ip++] & 0xff : 0;
            int o0 = i0 >>> 2;
            int o1 = ((i0 & 3) << 4) | (i1 >>> 4);
            int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
            int o3 = i2 & 0x3F;
            out[op++] = urlMap1[o0];
            out[op++] = urlMap1[o1];
            if (op < oDataLen) {
                out[op] = urlMap1[o2];
            }
            op++;
            if (op < oDataLen) {
                out[op] = urlMap1[o3];
            }
            op++;
        }
        return out;
    }
}